'Health of the mother is biggest factor in baby's size'
Newborn babies born to healthy, well-nourished mothers are strikingly similar in size the world over, scientists have shown.
On average, they have a body length of 49.4 centimetres (19.45 inches), an international study found.
Previously it was suggested that ethnicity was largely responsible for the widespread variation in the size of babies around the world.
The new research suggests race and ethnicity contribute little to baby size. What matters more is the education, health and nutrition of mothers, and the care they receive.
Overall no more than 4pc of differences in foetal growth and birth size could be attributed to population differences.
Scientists taking part in the Intergrowth-21st study looked at almost 60,000 pregnancies in urban areas of the UK, US, Brazil, China, India, Italy, Kenya and Oman.
Lead researcher Professor Jose Villar, from Oxford University, said: "Currently we are not all equal at birth, but we can be. We can create a similar start for all by making sure mothers are well educated and nourished, by treating infection and by providing adequate antenatal care.
"Don't say that women in some parts of the world have small children because they are predestined to do so. It's simply not true."
Findings from the study, funded by the Bill & Melinda Gates Foundation, are reported in the journal 'The Lancet Diabetes & Endocrinology'.
In 2010, an estimated 32.4 million babies were born undernourished in low-to-middle-income countries, representing 27pc of all live births globally.
Co-author Professor Zulfiqar Bhutta, from the Aga Khan University in Karachi, Pakistan, and the Hospital for Sick Children in Toronto, Canada, said: "The fact that when mothers are in good health, babies grow in the womb in very similar ways the world over is a tremendously positive message of hope for all women and their families."